U.S. patent number 4,568,453 [Application Number 06/650,895] was granted by the patent office on 1986-02-04 for apparatus and method for removing dust from particulate material.
Invention is credited to Henry E. Lowe, Jr..
United States Patent |
4,568,453 |
Lowe, Jr. |
February 4, 1986 |
Apparatus and method for removing dust from particulate
material
Abstract
Apparatus and method for removing dust from particulate
material, utilizing a tower or column having a passage with a
series of baffles on opposite sides over which the particulate
material cascades while air is drawn across the flow path of the
material to remove the dust dispersed in the material and adhering
to the surface of the particles of material. Air is drawn across
the passage from one side to the other by vacuum or suction from a
vacuum pump or the like. In performing the method using the
apparatus, the particulate material is introduced at the top of the
column and permitted to cascade down through the vertical passage
therein from one baffle to the next, and air is drawn inwardly
between the baffles on one side and outwardly between the baffles
on the opposite side of the column, and, as the air flows through
the material cascading between the baffles, it removes the dust
from the material. The apparatus can be used in conjunction with a
storage bin, or with a conveyor which removes the material as it is
discharged by the apparatus.
Inventors: |
Lowe, Jr.; Henry E.
(Cassopolis, MI) |
Family
ID: |
24610742 |
Appl.
No.: |
06/650,895 |
Filed: |
September 14, 1984 |
Current U.S.
Class: |
209/135; 209/137;
209/149; 209/154 |
Current CPC
Class: |
B07B
11/04 (20130101); B07B 4/04 (20130101) |
Current International
Class: |
B07B
4/04 (20060101); B07B 11/04 (20060101); B07B
4/00 (20060101); B07B 11/00 (20060101); B07B
004/04 () |
Field of
Search: |
;209/134,135,149,153,156,136,137,147,154 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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309361 |
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May 1929 |
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GB |
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316889 |
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Oct 1930 |
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GB |
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394062 |
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Jun 1933 |
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GB |
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515058 |
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Nov 1939 |
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GB |
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548983 |
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Nov 1942 |
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GB |
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558808 |
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Jan 1944 |
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GB |
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588347 |
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May 1947 |
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GB |
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Primary Examiner: Lutter; Frank W.
Assistant Examiner: Lithgow; Thomas M.
Attorney, Agent or Firm: Hobbs; Marmaduke A.
Claims
I claim:
1. An apparatus for removing dust from particulate material,
comprising:
a. a vertically disposed column having a material flow passage
therein and material inlet and outlet passageways near the top and
bottom of said column passage, respectively;
b. alternately arranged baffles disposed on opposite sides of said
passage, each having a downwardly and inwardly sloping portion with
upper and lower edges, the lower edge of the baffle portion on one
side of the column being positioned principally above the upper
edge of the next lower baffle portion on the opposite side of the
column;
c. air intake openings disposed between said baffles on one side of
said passage and extending from a point adjacent the upper edge of
one baffle portion to a point adjacent the upper edge of the baffle
portion immediately above the respective opening to provide a
substantially unrestricted opening from one baffle to the
other;
d. air outlet openings disposed between said baffles on the
opposite side of said passage and having upper and lower edges, the
upper edge of each of said outlet openings being disposed adjacent
the upper edge of the sloping baffle portion immediately above the
respective outlet opening, and the lower edge of each of said
outlet openings being disposed above a horizontal plane at the
lower edge of said respective sloping baffle portion, the air
outlet openings being substantially smaller in effective area than
said air intake openings;
e. a manifold means connected to said outlet openings;
f. a vacuum source; and
g. means for connecting said manifold means to said source of
vacuum for creating a flow of air from said intake openings to said
outlet openings through particulate material flowing downwardly in
said column passage from one baffle to another to remove dust from
the material.
2. An apparatus for removing dust from particulate material as
defined in claim 1, in which said baffles on each side of said
passage extend beyond the center of said passage and are spaced
from the opposite side of said passage so that said material
flowing through said passage must fall alternately from one baffle
to another baffle.
3. An apparatus for removing dust from particulate material as
defined in claim 2, in which said baffles are disposed at a
downwardly and inwardly extending angle of approximately
45.degree..
4. An apparatus for removing dust from particulate material as
defined in claim 1, in which projections are provided at the lower
lateral corners of said baffle portions for assisting in
controlling the flow of material from one baffle portion to the
other.
5. An apparatus for removing dust from particulate material as
defined in claim 4, in which said projections are tapered laterally
outward from the inner edges of the respective baffle portions to
form tabs of a generally triangular shape.
6. An apparatus for removing dust from particulate material as
defined in claim 1, in which a plenum is connected with said intake
openings and has port means connected to a source of air.
7. An apparatus for removing dust from particulate material as
defined in claim 6, in which said port means includes an opening
near the bottom of said plenum and a passage near the top of said
plenum.
8. An apparatus for removing dust from particulate material as
defined in claim 7, in which said port means near the top of said
plenum includes a conduit means connecting the upper part of said
plenum to said passageway at the top of said column passage.
9. An apparatus for removing dust from particulate material as
defined in claim 6, in which said plenum is a storage bin for the
cleaned particulate material.
10. An apparatus for removing dust from particulate material as
defined in claim 9, in which said column is disposed in said bin,
and said air intake openings in said column occupy the major part
of the space between said baffles on the respective side of said
column and serve as a discharge port for the cleaned material.
11. An apparatus for removing dust from particulate material as
defined in claim 6, in which a valve means is provided for
adjusting the size of said outlet openings for controlling the flow
of air through said column passage.
12. An apparatus for removing dust from particulate material as
defined in claim 1, in which a valve means is provided for
adjusting the size of said outlet openings for controlling the flow
of air through said column passage.
13. An apparatus for removing dust from particulate material as
defined in claim 12, in which said means for connecting said
manifold to a source of vacuum is connected to said manifold near
the upper end thereof.
14. An apparatus for removing dust from particulate material as
defined in claim 1, in which said means for connecting said
manifold to a source of vacuum is connected to said manifold near
the upper end thereof.
15. An apparatus for removing dust from particulate material,
comprising:
a. a vertically disposed column having a material flow passage
therein and material inlet and outlet passageways near the top and
bottom of said column passage, respectively;
b. alternately arranged baffles disposed on opposite sides of said
passage, each having a downwardly and inwardly sloping portion with
upper and lower edges;
c. air intake openings between said baffles on one side of said
passage extending adjacent the upper edge of the baffle portion to
a point adjacent the upper edge of the baffle portion immediately
above the respective opening to provide a substantially
unrestricted opening from one baffle to the other;
d. air outlet openings, substantially smaller in effective area
than said air intake openings, disposed between said baffles on the
opposite side of said passage and having upper and lower edges, the
upper edge of each of said outlet openings being disposed adjacent
the upper edge of the sloping baffle portion immediately above the
respective outlet opening, and the lower edge of each of said
outlet openings being disposed above a horizontal plane at the
lower edge of said respective sloping baffle portion; and
e. means for creating a flow of air from said intake openings to
said outlet openings through particulate material flowing
downwardly in said column passage from one baffle to another to
remove dust from the material.
16. An apparatus for removing dust from particulate material as
defined in claim 15, in which a manifold means is connected to said
outlet openings for receiving the dust-laden air from said outlet
openings.
17. An apparatus for removing dust from particulate material as
defined in claim 16, in which a plenum is connected with said
intake openings and has port means connected to a source of
air.
18. An apparatus for removing dust from particulate material as
defined in claim 15, in which projections are provided at the lower
lateral corners of said baffle portions for assisting in
controlling the flow of material from one baffle portion to the
other.
19. An apparatus for removing dust from particulate material as
defined in claim 18, in which said projections are tapered
laterally outward from the inner edges of the respective baffle
portions to form tabs of a generally triangular shape.
20. A method of removing dust from particulate material,
comprising:
a. passing the particulate material downwardly through a column
having a series of spaced baffles on which the material
successively falls, said baffles being arranged alternately from
side-to-side and sloping inwardly and downwardly in overlapping
relationship, with the lower edge of the baffle on one side of the
column being positioned principally above the upper edge of the
next lower baffle on the opposite side of the column, and with air
inlet openings beneath the baffles on one side of the column and
air outlet openings beneath the baffles on the opposite side, the
inlet openings being of a size substantially larger than the size
of said outlet openings;
b. subjecting the downwardly flowing material to a vacuum on the
last mentioned opposite side of the column;
c. producing a generally transverse flow of air, at a relatively
low velocity, from beneath each baffle on one side, thence through
the downwardly flowing material as the material passes from one
baffle to another, and then at a relatively high velocity, upwardly
beneath the next lower baffle on the opposite side, to separate the
dust from the particulate material; and
d. removing the dust laden air from the flowing particulate
material.
21. A method of removing dust from particulate material as defined
in claim 20, in which said air flows first inwardly and downwardly
between the baffles on one side and thence upwardly between the
baffles on the opposite side in close proximity to the underside
thereof, as the material passes from one baffle to another.
22. A method of removing dust from particulate material as defined
in claim 21, in which said transverse flow of air is produced by
subjecting said flowing material on to a vacuum on the opposite
side of the column.
23. A method of removing dust from particulate material as defined
in claim 20, in which said transverse flow of air is produced by
subjecting said flowing material on to a vacuum on the opposite
side of the column.
Description
BACKGROUND OF THE INVENTION
Many particulate materials used in industry and in the home contain
a substantial amount of dust which tends to become airborne when
the material is transferred or transported in bulk or when carried
on a conveyor or poured from a bag or other container, often
creating an environmental condition hazardous to the health of
workers in the vicinity, and/or producing an explosive mixture
capable of destroying the facility handling the material. This
condition is prevalent in the grain handling or milling industries
and in the mining, quarrying and processing of minerals. While the
dust in the particulate material is itself a particulate, for the
purpose of the description herein, the particulate material of
useful or desired size will be referred to as the "particulate
material", and the undesirable or smaller particles which can
readily become air-borne will be referred to as the "dust", the
difference often being merely in the size of the particles, with
the smaller particles being the component to be removed from the
base particulate material.
In the clay industry, particulate material is prepared for a
variety of uses, including oil and grease absorption and animal
litters, wherein the clay is heated to drive off the moisture and
then ground and graded to obtain a bulk material of substantially
uniform particle size. In the processing of this material, it is
first crushed and heated to drive off the moisture, and thereafter
screened and stored in bulk and/or bagged or otherwise packaged for
shipping. As the material passes through these various stages of
the operation, dust, i.e. relatively small undesirable particles,
is created in the particulate material from friction between the
particles and/or contact of the particles with the equipment,
thereby rendering the material less suitable for such uses as an
oil absorbent or animal litter. The dust and/or useful particles
may have an electro-static charge which causes the dust to adhere
to the desirable particles, and hence interfere with the separation
of the dust from those particles by conventional screening
equipment. In the past, screens, cyclones, surfactants, air
separators, or other air classification systems have been used or
tried, but these systems have either been expensive to install and
operate, have required excessive amounts of space in the production
operation, or have not produced subtantially dust-free
material.
SUMMARY OF THE INVENTION
It is one of the principal objects of the present invention to
provide an apparatus which is relatively simple in construction and
operation, and operates in an efficient and economical manner to
remove the dust from particulate material, and which can readily be
adapted to materials having different particulate or granular size
and/or bulk density.
Another object of the invention is to provide an apparatus of the
aforesaid type, which has no moving parts and can operate
continuously over extended periods of time without servicing, and
which can easily be maintained in optimum operating condition to
give a consistent and stable performance.
A further object is to provide an apparatus for separating dust
from particulate material, which is compact and can readily be
adapted to normal or standard production lines, and which can
conveniently be installed in existing bulk or conveyor systems.
Still another object of the invention is to provide a method for
removing dust from particulate material, the steps of which can be
integrated into existing production line or storage facilities and
easily controlled to remove substantially all of the dust from the
particulate, and which can effectively be performed economically in
a relatively limited amount of space.
These and other objects, which will become apparent from the
following description and accompanying drawings, are accomplished
by the present invention, which utilizes a tower or column having a
vertical passage with a series of alternate sloping baffles over
which the particulate or granular material cascades while air is
drawn across the flow path to remove the dust dispersed in the
material and adhering to the surface of the particles of material.
The baffles are disposed on opposite sides of the vertical passage
in the column, and air is drawn across the passage from one side to
the other by a vacuum or suction from a closely controlled source
of low pressure, such as a vacuum pump at a dust collector. In
performing the method using the foregoing apparatus, the
particulate material is introduced at the top of the column and
permitted to cascade down through the vertical passage therein from
one baffle to the next, and air is drawn inwardly between baffles
on one side and outwardly between the baffles on the opposite side
of the column. The major portion of the dust to be removed occurs
at the top of the column and the amount removed progressively
decreases as the material descends in the column. The nature and
quality of the material will determine the size of the apparatus or
system to be used, particularly with reference to the length or
height of the baffle column. Generally, the more dusty the material
is, the larger the column should be in height, to provide a greater
exposure of the material to the transverse air flow through the
column. The present dust removing apparatus and method are
applicable to most free-flowing materials, including grain,
fertilizer, minerals, crushed rock, feeds, seeds, and powders such
as granular soap materials.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of one embodiment of the dust removing
apparatus, shown installed in conjunction with a conveyor
system;
FIG. 2 is a vertical cross-sectional view of the apparatus, the
section being taken on line 2--2 of FIG. 1;
FIG. 3 is an enlarged, fragmentary, vertical cross-sectional view
of the baffle column shown in FIG. 2;
FIG. 4 is a vertical cross-sectional view of the baffle column
shown in FIG. 3, the section being taken on line 4--4;
FIG. 5 is a horizontal cross-sectional view of the column shown in
FIG. 3, the section being taken on line 5--5;
FIG. 6 is a vertical cross-sectional view of the column shown in
FIG. 3, the section being taken on line 6--6;
FIG. 7 is an elevational view of a bulk storage bin having the
present apparatus installed therein; and
FIG. 8 is a vertical cross-sectional view of the system shown in
FIG. 7, the section being taken on line 8--8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring more specifically to the drawings, and to FIGS. 1 through
6 in particular, numeral 10 designates generally an apparatus for
removing dust from particulate material, embodying the present
invention. Numeral 12 indicates a supply conduit for particulate
material to be cleaned, and numeral 14 indicates a belt conveyor on
which the cleaned particulate material is discharged for
transporting to the next station in the processing operation, such
as a bulk storage bin or a machine for bagging the material. The
main dust removing operation is performed in a column, indicated
generally by numeral 20, disposed in a housing 22, the column
having material inlet passageway 24 at the top of the housing and
material outlet passageway 26 at the bottom of the housing directly
above belt conveyor 14. The column can be used with different types
of equipment, as will be more fully explained hereinafter.
The dust removing column consists of side members 28 and 30, seen
in FIG. 5, side 28 having inwardly extending vertical flanges 32
and 34, and side 30 having inwardly extending vertical flanges 36
and 38. Connected to the inwardly extending flanges 32 and 36 are a
plurality of baffles 40, each of which has a panel 42 joined
rigidly thereto and secured at its outer ends to inwardly extending
flanges 32 and 36, thereby holding the baffles 40 firmly in place
in column 20. Joined integrally to flanges 34 and 38 are a
plurality of baffles 50, each having a panel 52 secured to flanges
34 and 38. The inner edges of baffles 50 are equally spaced between
the inner edges of baffles 40. The baffles 40 and 50 slope
downwardly and inwardly at approximately a 45.degree. angle, and
the edges of the two sets of baffles 40 and 50 overlap one another
so that the particulate material introduced through inlet
passageway 24 must follow a circuitous route from the inlet
passageway at the top to the outlet passageway 26 at the bottom.
Furthermore the lower edge of the baffle 50 is positioned
principally above the upper edge of the next lower baffle 40 on the
opposite side of the column. (FIG. 2) The two sides 28 and 30, the
baffles 40 and 50, and the respective panels 42 and 52, form a
rigid columnar structure which is essentially self-supporting and
is normally constructed of sheet or plate steel of sufficient
thickness and strength that it can be transported and installed as
a unit.
In order to remove the dust from the particulate material, a flow
of air is created across the path of the cascading material, the
air passing through a series of inlet openings 54 between the upper
edge of panel 52 and the lower side of the adjacent baffle 50.
After entering openings 54, the air flows through the material and
exits through a series of outlet openings 58 disposed between the
upper edge of panels 42 and the lower side of the adjacent baffle
40. The air outlet openings 58 are substantially smaller in
effective area than the air inlet openings 54. (FIG. 2) The
effective size of openings 58 is controlled by a door 60 secured to
each panel 42 by a pair of screws 62 and 64 extending through holes
in the respective panel and through slots 66 and 68 in the door 60,
the slots 66 and 68 permitting adjustment of the doors to decrease
or increase the size of openings 58, and thereby assisting in
controlling the amount of air passing transversely through the
column from opening 54 and the particulate material to opening 58.
Holes 58 are immediately below the underside of the baffles and
are, preferably, completely above the lower inner edge of the
respective baffles; thus, the dust-laden air passing through column
20 must flow upwardly to reach holes 58, thereby preventing or
minimizing the discharge of the larger particles of the particulate
material.
The housing contains an air inlet plenum or manifold 70 and an
outlet plenum or manifold 72, the inlet plenum having an air inlet
74 at the bottom and an air inlet 76 at the top of the plenum. The
opening 76 communicates with supply conduit 12 through passage 78
and opening 80; thus, the air which flows through openings 54 in
column 20 enters plenum 70 at both the top and bottom of the air
intake plenum. Outlet manifold 72 communicates with openings 58 and
with outlet 82, and through conduit 84, with a vacuum or suction
pump (not shown) which is connected to a dust collector (not
shown). The vacuum or suction pump and dust collector are
considered conventional, and are readily available on the market
and, hence, are not described in detail herein. The column can
readily be reached for service through a door 85 extending
virtually the full length of intake plenum 70, the door being
hinged along one side so that, when it is opened, it exposes most
of one side of column 20. As seen in FIG. 1, one side of housing 22
has several windows, indicated generally by numeral 86, to permit
an operator to observe the performance of the apparatus during
operation, so that adjustments can be made to obtain and maintain
optimum performance of the equipment.
To provide and maintain a uniform curtain of downwardly flowing
particulate material over the full width of the baffles between the
side walls 28 and 30 of the column, triangular tabs or projections
87 and 88 are provided at opposite corners at the inner edge of
each baffle. These projections distribute the material effectively
near the two side walls and prevent the formation of open or thin
areas in the curtain, where the air can flow freely and at greater
velocity than at the center of the curtain. When the openings or
thin areas occur in the curtain, there is a tendency for the faster
flowing air through those areas to remove larger or heavier
particles than the slower flowing air where there are no openings
or where the curtain is thicker. Thus, these projections, by
maintaining substantially uniform distribution and flow of material
over the inner edges of the baffles, prevent or minimize the
removal from the curtain of particles of a size within the desired
range, thereby rendering the dust removing operation more efficient
and economical, with less loss of the basic particulate
material.
In the use and operation of the embodiment of the present invention
illustrated in FIGS. 1 through 6, dust-containing particulate
material is fed through inlet passageway 24 of column 20, from
which it cascades downwardly through the passage in the column,
alternately from a baffle on one side to a baffle on the opposite
side. As the material passes downwardly through the column from one
baffle to another, air drawn through plenum 70 into the column
passes from intake openings 54 through the curtain of falling
particulate material, thereby removing the dust therefrom and
carrying it to and through outlet openings 58 into outlet manifold
72. The dust-laden air in manifold 72 is drawn into outlet passage
82, thence through conduit 84 to the vacuum or suction pump and to
a dust collector. The greater part of the dust is removed from the
particulate material in the upper part of column 20; however, the
cleaning action continues until the particulate material flows from
the column into outlet passageway 26. The air-flow into plenum 70,
through the column, and from the manifold 72, is indicated by
arrows showing the air passing through openings 74 and 76 into the
intake plenum, and thence through inlet openings 54 and through the
material to outlet openings 58 and outlet manifold 72, from which
it is drawn by the suction or vacuum to the dust collector. The
cleaned material flows downwardly through outlet passageway 26 onto
a moving conveyor belt, and is transported either to a storage bin
or to the next step in the processing operation, such as a machine
for bagging the cleaned particulate material. The volume of the
particulate material flowing through the column 20, at any
particular time, is controlled by a suitable valve means in conduit
12 or in the equipment thereabove, and the air flow through the
column from inlet openings 54 to outlet openings 58 is controlled
by suitable valves in conduit 84, or by regulation of the suction
or vacuum pump. Air flow can also be regulated, within limits, by
shifting doors 60 upwardly or downwardly to vary the size of
openings 58.
The embodiment of the invention shown in FIGS. 7 and 8 involves a
baffle column similar in most respects to the baffle column shown
in the preceding figures; consequently, the same numerals will be
used to identify similar parts in the column. In this embodiment,
the dust removing column is used in conjunction with a bin 90,
having a tower 92 with a door 94 therein for observing the
operation and servicing the equipment. The air for openings 54 in
the column enters the upper part of bin 90 through opening 96 in
the upper end of tower 92 and passes downwardly into the inner
chamber of the bin, and thence passes through the inlet openings
54, through the curtain of particulate material, and outwardly
through outlet passages 58. The bin can be of different sizes and
shapes and, in this embodiment, the bin serves as the air intake
plenum for column 20, so that when the air flows through passage
96, it passes into chamber 100 of the bin, and thence is
distributed to intake openings 54. The air then passes through the
particulate material and outwardly through outlet passages 58 into
a manifold 102 extending substantially the full length of the
column. The manifold is connected to a suction or vacuum pump and
dust collector by conduit 104 near the bottom of the column. The
manifold is not connected to chamber 100 of the bin, except through
the column, and, hence, the vacuum created in the manifold is
effectively transmitted through the column to produce the desired
air flow from chamber 100 to the manifold and thence to the dust
collector. The particulate material is fed to the column through
tube 104 and inlet passageway 106 at the top of the column. The
material to be cleaned passes downwardly through the column and is
discharged initially at the bottom of the bin, and, as the cleaned
material accumulates in the bin and rises above the lower part of
the column, the cleaned material then flows outwardly through
openings 54 and continues to fill the bin. While the full capacity
of the dust removing column is diminished as the material
accumulates, this is normally not significant, in that the greater
part of the dust is removed from the particulate material in the
upper portion of the column. The cleaned material in the bin is
removed from time-to-time through discharge opening 110 at the
bottom of the bin.
The method of the present invention has been set forth in the
description of the operation of the apparatus, with respect to both
embodiments, and involves essentially causing the material to
cascade downwardly through the column over the baffles, while
subjecting the material to a transverse flow of air therethrough as
the material falls from one baffle to another. In the embodiment of
FIGS. 7 and 8, this operation is modified by the accumulation of
cleaned material in the bin, in that the flow of the cleaned
material from the column is diverted from the discharge end of the
column to the openings 54 as the cleaned material accumulates in
the bin.
It is seen that the present apparatus and method provide an
effective way of removing dust from particulate material in an
economical and convenient manner, in a relatively small amount of
space. The only moving elements in the dust removing apparatus are
the flow of the material being cleaned and the air flow through the
material created by the vacuum or suction pump, which normally does
not form a structural part of the apparatus. Thus, the apparatus
can function effectively over long periods of time with little
service or maintenance, and can be conveniently and effectively
controlled to maintain optimum performance. While, as mentioned
previously, the apparatus and method disclosed herein are primarily
for use in removing the relatively small particles referred to
herein as dust, which can easily become air-borne, from the
relatively large particles of the base particulate, both the
apparatus and method can be used to separate different size and/or
density particles from one another, even though the small size
particles may not normally be classified as dust particles. Hence,
depending on the velocity of the transverse air flow, the apparatus
and method can be used to screen and grade material according to
size and/or density. As used in the claims, the term "dust" refers
to the smaller of two particle sizes in a material, which normally
can readily become air-borne, as distinguished from the larger
particles of the material.
While only two embodiments of the apparatus and method for removing
dust from particulate material have been described in detail
herein, various changes and modifications may be made without
departing from the scope of the present invention.
* * * * *